Rapid Development of Rapid Development of Radio Astronomy Radio Astronomy

Instrumentation Using Instrumentation Using Open Source FPGA Boards, Open Source FPGA Boards,

Tools and LibrariesTools and Libraries

Center for Astronomy Signal Processing and Electronics ResearchCenter for Astronomy Signal Processing and Electronics Research

CASPER The Friendly...Group Helping Open-source Signal-Processing Technology? (GHOST)

✴ Goal is to Develop High Performance Signal Processing Infrastructure for the Astronomy Community and Beyond.

✴ Open Source Everything.

✴ Use Commodity Off-the-shelf Hardware Where Possible.

✴ Provide Training and Tutorials (Wiki, Video Lectures, Workshops etc...)

✴ Promote Collaboration (30+ Universities and Observatories.

✴ Do Not Necessarily Concentrate or Specialize in Turn-Key Instruments.

The Problem With The Current Hardware Development Model

✴Takes Five to Ten Years

✴Cost Dominated by NRE Because of Custom Boards, Backplanes and Protocols

✴Antiquated by the Time of Release

✴Each Observatory Designs From Scratch

Conventional Radio Astronomy Instrument Rack

Conventional Radio Astronomy Compute Board

Solution:✴ Low Number of Board

Designs

✴ Can be Upgraded Piecemeal or All Together

✴ Reusable

✴ Standard Signal Processing Model Consistent Between Upgrades

Modular Hardware

IBOB Board

BEE2 BoardRoach Board

Modular Gateware

✴ Gateware is the Design Logic of FPGAs (Between Hardware and Software)

✴ Signal Processing Libraries Which Do Not Need to be Rewritten Every Hardware Generation (FFTs, PFBs, DDC)

✴ Implement Industry Standard Communication Protocols (10 Gb Ethernet, UDP)

Platform-Independent Parameterized

Gateware

TransposerPFB/FFT

BufferIntegrator

ADC

iBOB

“Pocket Spectrometer”

What is an FPGA?✴ FPGA stands for Field

Programmable Gate Array - as the name implies, they consist of a collection of reprogrammable digital logic elements ✴ The first commercially

available FPGA was introduced in 1985.

✴ Common applications include telecommunications, cryptography, image processing, defense systems, etc..

What is an FPGA?✴ FPGAs are programmable logic

elements - bread-boards on a chip that can have their circuits reconfigured to perform specific tasks very efficiently.

✴ In addition to simple reconfigurable logic gates (AND, XOR, etc..) FPGAs often contain memory and dedicated multipliers.

Programming FPGAs

module addsub (a, b, addnsub, result);input [7:0] a;input [7:0] b;input addnsub;output [8:0]

result; reg [8:0] result; always @(a or b or

addnsub) begin if (addnsub)result = a + b;

else result = a - b;endendmodule

Conventional Method:Hardware Description Languages (HDL) - Verilog, VHDL

Conventional Method:Hardware Description Languages (HDL) - Verilog, VHDL

‣Adding and Subtracting in Verilog ‣Adding and Subtracting in C

x = a + b;

Programming FPGAsA Graphical Approach:A Graphical Approach:

The Leuschner Spectrometer

The Leuschner Spectrometer

Step 1:

Analog to Digital Conversion

In IDL:result=sampler(..)

Step 1:

Analog to Digital Conversion

In IDL:result=sampler(..)

The Leuschner Spectrometer

Step 2:

Channelization

In IDL:spectra=fft(..)

Step 2:

Channelization

In IDL:spectra=fft(..)

The Leuschner Spectrometer

Step 3:

Power and Accumulation

In IDL:result = total(..)

Step 3:

Power and Accumulation

In IDL:result = total(..)

Synthesis

Simulink

HDL Code

Place and Route

Binary FPGA Programming Instructions (Bitstream)

The “Compilation” Process

Download to IBOB

Leuschner Spectrometer System

IF at 150 MHz

100 Mbit Ethernet (UDP)

IDL “takespec”- receives UDP packets- stores payloads in raw binary format .log file

IDL “readspec”- opens and reads binary .log files- checks for dropped packets- converts to native IDL array

IDL “takespec”- receives UDP packets- stores payloads in raw binary format .log file

IDL “readspec”- opens and reads binary .log files- checks for dropped packets- converts to native IDL array

High-Res Spectrometers

4-input ‘Pocket’ Correlators

VLBI Channelizers

An 32-input Correlator:

16 iBOBs + 1 BEE2

An Arbitrary Sized Correlator:

Using a commercial switch we can solve the interconnect problem and enable highly scalable instruments.

A Beowulf Cluster for Radio Astronomy

The Fly’s EyeThe Fly’s EyeA Search for Highly Energetic Dispersed A Search for Highly Energetic Dispersed

Radio Transients using the Allen Radio Transients using the Allen Telescope ArrayTelescope Array

Fly’s Eye Motivation

Frequency vs. Time Waterfall (Lorimer 2007)

Exciting Results From Lorimer et al.

• Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, 2007.

Possible Sources of Bright Short-Duration Radio Pulses:

‣Evaporating primordial black holes‣Coalescing massive objects (NS-NS, NS-BH merger events)‣Emissions from cusps on cosmic strings‣ET‣RFI

Pulses of this type could serve as an invaluable cosmological probe of the intergalactic medium.

Fly’s Eye Timeline

‣November 19, 2007 - Dan Werthimer and Geoff Bower have lunch to discuss transient search projects using the ATA.

‣November 20, 2007 - A group of mostly undergraduate students to begin building a transient instrument.

‣December 22, 2007 - Fly’s Eye Team installs Fly’s Eye at ATA.

‣February, March 2008 - Conducted 500 hours of weekend observations.

‣April 2008 - Present - Data analysis underway

• Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, 2007.

September 27, 2007

• Fly’s Eye First Light

December 22, 2007

Fly’s Eye Basics44 independent spectrometers - constructed using a system of eleven iBOB/iADC quad spectrometers

Built using open-source CASPER hardware and software libraries in about one month.Sky Coverage:

22 - 42 beams100-200 square degrees

Spectrometer Specifications (each):208 MHz bandwidth, at 1430 MHz128 spectral channels0.625 mS readout

Distributions:Spatial, DM, Power, Pulse Width

Sky Coverage:22 - 42 beams100-200 square degrees

Spectrometer Specifications (each):208 MHz bandwidth, at 1430 MHz128 spectral channels0.625 mS readout

Distributions:Spatial, DM, Power, Pulse Width

Fly’s Eye Rack at ATA

Other Applications...VLBI Mark 5B Data Recorder - Haystack, NRAO

Transient Searches - Fly’s Eye at ATA - UC Berkeley and Cornell

Beamforming ATA & SMA - Weintroub, Urry, Milgrome et al.Oxford - Zarb-Adami et al.SETI:Arecibo - Werthimer, et al.JPL/UCB Deep Space Network - Levin et al.

Pulsar Timing and Searching:NRAO, Berkeley, Swinburne, Jodrell Bank et al.

Correlators and Imagers:ATA - Wright et al.EOR - Backer, Bradley, Parsons et al.CARMA Next Gen - Hawkins, Wright et al.MeerKAT/SKA South Africa - Jonas, Langman, et al.GMRT Next GenOthers....